Final answer:
To land, an aircraft's speed must be reduced safely below its stall speed, as the lift is reduced.
Step-by-step explanation:
In order for an aircraft to land, its speed must be reduced safely below its stall speed, as the lift generated by the wings is reduced to levels less than its weight.
Stall speed is the minimum speed at which an aircraft can maintain level flight, and it is determined by factors such as the shape of the wings, the angle of attack, and the weight of the aircraft.
When the aircraft's speed drops below the stall speed, the wings can no longer generate enough lift to support the weight of the aircraft, and it begins to descend towards the ground for landing.